Device for detection of power-off
First Claim
Patent Images
1. A device for detecting a power-off of external input power from a power supply device, comprising:
- a detection unit for generating an induced current in response to an AC current provided by the power supply device;
a voltage supply unit for converting the induced current generated by the detection unit into a detection voltage; and
a voltage comparison unit for comparing the detection voltage provided by the voltage supply unit and a reference voltage, and for providing a power-off detection signal when there is a difference between the detection voltage and the reference voltage;
wherein the detection unit comprises a transformer which includes a first coil which forms a magnetic flux in response to the AC current provided by the power supply device, a second coil which is responsive to the magnetic flux formed by the first coil for generating an induced current which is smoothed and rectified so as to provide a DC voltage, via an output circuit, to an electronic appliance, and a third coil which generates the induced current in response to the magnetic flux formed by the first coil;
said device further comprising a voltage divider connecting the output circuit to an inverting input of the voltage comparison circuit for providing a divided voltage thereto as the reference voltage; and
wherein the voltage comparison circuit provides the power-off detection signal via the output circuit, to the electronic appliance, whereby the electronic appliance is safely prepared for power-off.
1 Assignment
0 Petitions
Accused Products
Abstract
A power-off detection device is formed without use of a photo coupler, which is expensive and occupies a relatively large area. The power-off detection device rectifies AC power, provided as external input power from a power supply device, into DC power, detects the power-off of the external input power from the power supply device as provided to an electronic appliance, provides a power-off detection signal to central control means of the electronic appliance, and enables the central control means to prepare for the power-off, thereby reducing manufacturing cost of the power supply device, and achieving miniaturization thereof.
33 Citations
18 Claims
-
1. A device for detecting a power-off of external input power from a power supply device, comprising:
-
a detection unit for generating an induced current in response to an AC current provided by the power supply device; a voltage supply unit for converting the induced current generated by the detection unit into a detection voltage; and a voltage comparison unit for comparing the detection voltage provided by the voltage supply unit and a reference voltage, and for providing a power-off detection signal when there is a difference between the detection voltage and the reference voltage; wherein the detection unit comprises a transformer which includes a first coil which forms a magnetic flux in response to the AC current provided by the power supply device, a second coil which is responsive to the magnetic flux formed by the first coil for generating an induced current which is smoothed and rectified so as to provide a DC voltage, via an output circuit, to an electronic appliance, and a third coil which generates the induced current in response to the magnetic flux formed by the first coil; said device further comprising a voltage divider connecting the output circuit to an inverting input of the voltage comparison circuit for providing a divided voltage thereto as the reference voltage; and wherein the voltage comparison circuit provides the power-off detection signal via the output circuit, to the electronic appliance, whereby the electronic appliance is safely prepared for power-off. - View Dependent Claims (2, 3, 4, 5, 6, 13, 14, 15)
-
-
7. A device for detecting a power-off of an external input power from a power supply device, comprising:
-
a transformer for generating an induced current in response to AC power provided by the power supply device; a voltage supply unit for smoothing and rectifying the induced current generated by the transformer to provide a detection voltage; and a voltage comparison unit for comparing the detection voltage provided by the voltage supply unit and a reference voltage, and for providing a power-off detection signal when there is a difference between the detection voltage and the reference voltage; wherein the transformer comprises a first coil which forms a magnetic flux in response to the AC current provided by the power supply device, a second coil which is responsive to the magnetic flux formed by the first coil for generating an induced current which is smoothed and rectified so as to provide a DC voltage, via an output circuit, to an electronic appliance, and a third coil which generates the induced current in response to the magnetic flux formed by the first coil; said device further comprising a voltage divider connecting the output circuit to an inverting input of the voltage comparison circuit for providing a divided voltage thereto as the reference voltage; and wherein the voltage comparison circuit provides the power-off detection signal via the output circuit, to the electronic appliance, whereby the electronic appliance is safely prepared for power-off. - View Dependent Claims (8, 9, 10, 11, 12, 16, 17, 18)
-
Specification